Control of microbial growth in mineral slurries is a major concern for industrial manufacturers. Conventionally, mineral slurries are conserved using biocides. Among the widely used biocidal formulations, some contain isothiazolinones, such as 1,2-benzisothiazolin-3-one (also referred to as “BIT”). However, as noted in Patent Application Publication No. 2009/0120327, although such formulations are effective against many bacteria, they nevertheless have a lesser effectiveness against certain bacterial species. Accordingly, to compensate for this lack of efficacy against certain microbes, a large amount of BIT is typically needed to obtain reasonable performance.
For economic, environmental and toxicological considerations, it is desirable to improve the antimicrobial efficacy at a specific use level and/or reduce the amount of the biocide required for satisfactory performance in industrial applications. US Patent Application Publication No. 2007/0275094 discloses that the use of a zinc compound selected from the group consisting of zinc salts, zinc oxides, zinc hydroxides, and combinations, can improve the antimicrobial efficacy of an isothiazolin-3-one-containing composition, such as a BIT-containing one, as compared to a composition that does not contain the zinc compound. Despite of the improvements attributed to the compositions disclosed in the '094 publication, there is still a need in the biocides manufacturing community for an antimicrobial composition that is effective for use in wet state preservation of mineral slurries.
The present invention provides one such alternative.